A need exists for an easy, accurate and quick technique for monitoring ultraviolet lasers. Monitoring the beam profile of an ultraviolet laser beam is critical in many applications and laser developments. Ultraviolet lasers are used in a wide variety of applications and experiments including laser surgery, laser welding, laser fusion, laser isotope separation, atomic and molecular physics research and laser spectroscopy. In practically all these applications, it is important have accurate beam profile measurements in order to achieve efficient and safe operation and meaningful experimental results.
Known methods for monitoring laser beam profiles are generally difficult, expensive and intrusive of the laser beam. For example, a laser beam profile could be obtained by placing photodiodes in the beam to observe it, and reticon multi-channel plates are made for this purpose. There are numerous drawbacks to this technique. The first is cost. The photodiode plates are expensive and computers or other sophisticated electronics are required for data readout. Operation is difficult. The plates must be carefully placed in the beam. Then, the plate must be moved parallel to the beam and multiple samples must be taken in order gather information as to the longitudinal beam profile. The placement and movement of the plates must be done precisely and are sources of difficulty and error. Also, the damage threshold of such devices is generally low (about 0.1 mJ/cm.sup.2) and the dynamic range is narrow compared to the present invention. Finally, this technique of monitoring a laser beam invades and blocks the laser beam which may be undesirable in some applications.
Another known technique for measuring or monitoring ultraviolet laser beams uses photographic film placed in the path of the laser beam. Again this technique is difficult, requires precise positioning of the film and requires multiple samples of the laser beam at different positions to obtain longitudinal profile information of the beam.